The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Generally, the oil pump of a vehicle engine is usually a rotor pump. The rotor pump comprises a shell, and inner and outer rotors eccentrically disposed in the shell. The shell comprises an inlet connected to a low-pressure oil chamber, and an outlet connected to a high-pressure oil chamber. When the engine is in operation, the inner rotor is driven to rotate with the outer rotor. With the rotation of the inner rotor and the outer rotor, the low-pressure oil injected through the inlet is transformed to high-pressure oil and then discharged from the outlet. However, in conventional oil pumps, the oil in the high-pressure oil chamber may leak into the low-pressure oil chamber from the high-pressure oil chamber due to a high pressure in the high-pressure oil chamber, so that the pressure in the high-pressure oil chamber may be decreased or lost, thus reducing the efficiency of the pump oil.